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Calculate number of pairs Whose LCM is 800 and HCF is 20?

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Best answer
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Number of pairs whose LCM = 800 and HCF = 20

Let the numbers be x and y. Now Highest Common Factor = 20 implies numbers are

a = 20 * x

b = 20 * y

Least Common Multiple = 800 implies  20 * x * y = 800

x * y = 40

Number of values (x,y) such that x*y = 40 and HCF of (x,y) = 1 because when taking LCM there was no common factor left between x and y  are (1,40)  (5,8)

Corrosponding pairs are  (20,800) (100,160) = 2

selected
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Total 4 pairs: (20.800), (800,20), (160,100), (100,160)

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